random | 易学教程

Trying to shuffle to generate a random number from an array and splice, but keep getting undefined for the last element that's left in the array

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问题 Here, I can generate random numbers that do not repeat. Below is the code for the same. <body> <div id="bingo"> <script> let numbers = new Set() .add("B1") .add("B2") .add("B3") .add("B4") .add("B5") .add("B6") .add("B7") .add("B8") .add("B9") .add("B10"); let called = Array.from(numbers); let display = new Array(); function getRandomNum() { function rando() { for (let i = called.length - 1; i > 0; i++) { const j = Math.floor(Math.random() * called.length); const number = called[i]; called[i]

Trying to shuffle to generate a random number from an array and splice, but keep getting undefined for the last element that's left in the array

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机器学习超详细实践攻略(9)：手把手带你使用决策树算法与调参

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决策树算法在工业中本身应用并不多，但是，目前主流的比赛中的王者，包括GBDT、XGBOOST、LGBM都是以决策树为积木搭建出来的，所以理解决策树，是学习这些算法的基石，今天，我们就从模型调用到调参详细说说决策树的使用方法。一、什么是决策树既然要用决策树，那么我们首先要知道决策树的基本原理。初听到决策树这个名字的时候，我觉得他是一种最不像机器学习算法的算法。因为这不就是编程里最基本的if-else选择语句嘛，还能有多厉害？而且我们生活中的和决策树相关的例子比比皆是，假如你出去买东西，如果价格合适，那就买下来，如果价格太高，那就和商家讨价还价，如果商家同意打折，那就买下来，如果商家不同意便宜点，那就放下东西走人。这就会构建出下图这样的一个决策树。别急，决策树算法之所以能成为机器学习十大算法，必然有其过人之处。仔细想想，决策树算法并不是单纯地进行决策，而是通过数据集让程序学会像人一样做这一系列的决策过程。所以决策树算法的核心是要解决两个问题： 1）如何从数据集中找出最佳分枝？ 2）如何在合适的时候让决策树停止生长，防止过拟合？几乎所有与决策树有关的模型调整方法，都逃不开这两个核心问题。关于第一个问题，一个数据集必然给出了很多的特征，先按照哪个特征来高效地划分数据集，是决策树需要解决的最大问题。当然，我们完全可以按照特征从头到尾顺次来划分数据集，但是，这样做其实并不好

Selecting one random data from a column from multiple rows in oracle

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问题 I am creating a view that needs to select only one random row for each customer. Something like: select c.name, p.number from customers c, phone_numbers p where p.customer_id = c.id If this query returns: NAME NUMBER --------- ------ Customer1 1 Customer1 2 Customer1 3 Customer2 4 Customer2 5 Customer3 6 I need it to be something like: NAME NUMBER --------- ------ Customer1 1 Customer2 4 Customer3 6 Rownum wont work because it will select only the first from all 6 records, and i need the

VBA/Macro to copy random rows based on multiple conditions

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问题 I need help to be able to get random rows from another workbook with specific conditions: If i click a button/run a macro, I should get something like this : 4 random rows for all rows that has "AU" 1 random row for all rows that has "FJ" 1 random row for all rows that has "NC" 3 random rows for all rows that has "NZ" 1 random row for all rows that has "SG12" ALL FROM Raw Data_Park Sampling.xlsx " Sheet1 " sheet and paste it to Park Sampling Tool.xlsm " Random Sample " sheet. All should

First Name Generator not working

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问题 I was attempting to make a random name generator and this is the code I came up with: private void GenerateName() { if (GeneratedName == "") { GenerateConsonant(); consonantCurrent = consonant1; GenerateVowel(); vowelCurrent = vowel1; GenerateConsonant(); consonantCurrent = consonant2; GenerateConsonant(); consonantCurrent = consonant3; GenerateVowel(); vowelCurrent = vowel2; } GeneratedName = consonant1 + vowel1 + consonant2 + consonant3 + vowel2; } private void GenerateConsonant() { Random

Javascript Dynamic Variable (Random number added)

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问题 How do I create a dynamic variable in Javascript? For example, I have: var myAwesomeText = "Hello World!" But now I want the varible MyAesomeText to have a random number attached to it every time the page is refreshed. So it would instead look like something like this: var myAwesomeText12345 = "Hello World!" And most importantly, how do I call that that new random variable back once the random number has been assigned to it? (i.e: alert(???);) I've tried something like this, but I'm going

What is the best way to random 1000 row (not duplicate row) from mysql?

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问题 What is the best way to random 1000 row (not duplicate row) from mysql ? Now i use this 1. get all data(id row) in to array. 2. Random position of array 1000 position. 3. i will get 1000 row (not duplicate row) But, it's very slow process, Do you have easy way to get random 1000 row (not duplicate row) ? 回答1: Well from the comment you are also satisfied with a theoretical answer. If you have your array with all rows, use array_unique() to get rid of duplicate rows then use shuffle() to mix

Update a table using CTE and NEWID()

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问题 I want try update a table using random values from the same table, but the original table don´t have a identity to follow or any other number column... WITH cteTable1 AS ( SELECT ROW_NUMBER() OVER (ORDER BY NEWID()) AS n, ENDE_NO_Address FROM TableX ) UPDATE TableX SET ENDE_NO_Address = ( SELECT ENDE_NO_Address FROM cteTable1 WHERE cteTable1.n = This is the problem... tnks for the help 回答1: declare @T table(Col1 varchar(10)) insert into @T values (1),(2),(3),(4),(5) ;with cte as ( select *,

What is a thread-safe random number generator for perl?

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问题 The core perl function rand() is not thread-safe, and I need random numbers in a threaded monte carlo simulation. I'm having trouble finding any notes in CPAN on the various random-number generators there as to which (if any) are thread-safe, and every google search I do keeps getting cluttered with C/C++/python/anything but perl. Any suggestions? 回答1: Do not use built-in rand for Monte Carlo on Windows. At least, try: my %r = map { rand() => undef } 1 .. 1_000_000; print scalar keys %r, "\n"